To measure the effectiveness of the antacid tablet, I will measure the acidity of the gastric acid with a litmus paper and then add the antacid tablet, after the tablet has fully dissolved into the gastric acid and does not seem to be reacting with the gastric acid. After doing this, I will measure the Ph level of the acid once again with litmus paper, if the paper changes to a lighter colour, we will know that the antacid tablet worked. The lighter the colour of the paper, the more effective the tablet will be.